Date of Award

3-2020

Document Type

Thesis

Degree Name

Master of Science in Nuclear Engineering

Department

Department of Engineering Physics

First Advisor

Abigail Bickley, PhD

Abstract

Thermal Ionization Mass Spectrometry (TIMS) is an invaluable tool in nuclear forensics as it enables isotopic assays of actinides to be measured, permitting analysis to include special nuclear material isotopic assays, nuclear reactor monitoring, and treaty verification. In one method of measurement for the TIMS system, samples are deposited in solution form on high-purity rhenium filaments. The filaments are heated to evaporate the solvent, and then further heated to cause sample ionization, permitting the sample to be transmitted through a magnetic field which separates ions based on mass to charge ratio into detectors for counting. Heavier ions will be deflected less by the magnetic field than lighter ions with equivalent charges. Critical to the function of TIMS is the rhenium filaments themselves; any variability that suppresses ionization of the samples can lead to reduction in the number of ions detected. This research examines twenty-four filaments utilized in TIMS that have already been used for actinide analysis, with varying degrees of ionization efficiency. By examining the surface of the filaments using scanning electron microscopy (SEM), energydispersive x-ray spectroscopy (EDS), optical microscopy and electrical conductivity analysis, this research determined that there was correlation between filament shape and reported filament efficiency.

AFIT Designator

AFIT-ENP-MS-20-M-107

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